The Complete Chloroplast Genome of Inula britannica: Unraveling the Phylogeny, Evolution, and Taxonomic Significance of the Genus Inula

Inula britannica is a significant botanical species of plant in the Asteraceae family. The dried capitulum of this plant has been utilized as a traditional Chinese herbal remedy, exhibiting therapeutic properties in treating edema, alleviating nausea, and preventing vomiting. The formal designation for Inula britannica has been assigned to Pentanema britannicum. The whole chloroplast genome of I. britannica was constructed de novo in this study. The genomic characteristics were assessed and subsequently compared to those of five Inula species. I. britannica’s chloroplast genome had a length of 150,774 base pairs. The observed structure had a characteristic quadripartite arrangement, comprising a substantial single-copy section, a smaller single-copy region, and a pair of inverted repeat regions, measuring 82,451 bp, 18,423 bp, and 24,950 bp in length, respectively. The genome has been shown to have 109 distinct genes, comprising 79 protein-coding genes, four rRNA genes, and 26 tRNA genes. The chloroplast genome of I. britannica was found to have 49 lengthy repetitive sequences and 69 simple sequence repeats. The findings of the phylogenetic analysis revealed a significant correlation among I. britannica, I. janopinca, and I. linariifolia, followed by I. hupehensis. Our proposal suggests that “Inula britannica” is a more appropriate label for this particular species than “Pentanema britannicum.” Combining the K2p, ecorPrimers, and DNA polymorphic analysis results, eight regions can be distinguished from four Inula species after PCR and sangger sequencing. The reconstruction of ancestral character states revealed a series of changes from long spurs to alternative petal forms in the Inula species. The investigation of divergence time revealed that Inula underwent diversification during the late Pliocene period, specifically around 3.245 Mya. These findings will aid in establishing its evolutionary connections and taxonomy classification.